Gas turbine systems are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor, one or more combustors, and a turbine. Compressed air is generated in the compressor and provided to the combustor where the compressed air is mixed with fuel and combusted. Hot combustion gases flow from the combustor to the turbine in order to drive the gas turbine system and generate power.
In gas turbine systems, a fuel system supplies fuel to the combustor. In order to avoid unintended combustion outside of the combustor, the fuel system is configured to segregate fuel bearing piping from piping bearing other system fluids such as hot air or secondary fuels. In many gas turbine systems, the fuel system utilizes an inert gas to segregate the fuel from other system fluids. In such gas turbine systems, to maintain fluid separation between the fuel and other system fluids, the fuel system fills a cavity between the piping bearing fuel and the piping bearing other system fluids with the inert gas and maintains the inert gas at a pressure greater than the pressures of the fuel and other system fluids.
Currently to maintain fluid separation in a gas turbine, the inert gas separating the fuel and other system fluids is kept at a constant predetermined pressure. The predetermined pressure is determined by adding a safety margin to a historical maximum pressure of the fuel and other system fluids based on a worst-case scenario of turbine operating conditions. This method has often resulted in very high and overly conservative inert gas pressure requirements because many factors can affect the pressures of the fuel and other system fluids such as the ambient temperature of air entering the turbine and the load on the turbine. In turn, the high inert gas pressure requirements of the current method have also resulted in high inert gas flow rates, large high pressure inert gas storage requirements, and non-flexible control limits for system operation.
Accordingly, new systems and methods for monitoring fluid separation in a gas turbine are needed that account for changes in the required pressure of the inert gas.
In addition, within the fuel system, valves are used to control the flow of the fuel and other system fluids. Maintenance of these valves is vital to the operational efficiency and safety of the gas turbine system. For example, a leaking valve may result in unscheduled shutdowns of the turbine system or dangerous mixing of fuel and other system fluids. Currently, physical inspection is the primary method of determining the maintenance condition of valves in the fuel system. However, physical inspections are expensive and time consuming because they often require taking the turbine out of operation. Also, it is difficult to account for certain valve maintenance issues via physical inspection.
Accordingly, new systems and methods for monitoring the health of valves in gas turbines are needed in order to avoid costly shutdowns.